Right.
I think it works in linux with no problems (based on earlier experience with more detailed programs to produce graphs).
Could the standard paths have changed? So, what is your gretl preference setting for the path to octave? Is it correct? Can you run any octave foreign block at all?
The issue is that I was able to run this program under windows 7 with earlier gretl and octave versions, in particular it works under gretl version up to 2016d and old octave versions - works with octave 3.4.3. However, under win 7 it does not work with late octave versions - does not work with octave 4.2.1.
In any case, I cannot make it work under win 10, no matter which version of gretl (I have used 1.9.92, 2016d, 2017d) and octave (3.4.3, 4.2.1) I use.
Yes we recently had a discussion about it on the devel list (thread "integrating gnuplot's multiplot"), although not very deep. I guess it will boil down to putting together a function package, I would be optimistic that the ETA is this year, but more pessimistic about this summer.
P.S. I originally started coding with octave because gretl does not offer a facility to produce subplots (graphpage is an imperfect substitute, and accepts only up to 8 graphs I think, while scatters accepts only one variable on each graph). I also did not like the idea of learning another language just to plot, when I am familiar with matlab / octave. Any plans for such a feature?